Bidirectional anisotropic reflectance of snow and sea ice in AVHRR channel 1 and channel 2 spectral regions. II. Correction applied to imagery of snow on sea ice

摘要

For pt.I see ibid., vol.37, no.1, p.543-54 (1999). Advanced Very High Resolution Radiometer (AVHRR) images acquired over the Arctic Ocean often show strong bidirectional reflectance of snow on sea ice. The observed anisotropic reflectance characteristics of these images are consistent with the theoretical analysis presented in Part I of this study. The anisotropic reflectance at the top of atmosphere (TOA) is simulated by radiative transfer modeling and the results show a good model-observation agreement. Based on these modeling results, a method was developed to correct the effect of anisotropic reflectance on AVHRR images in channels 1 and 2. Results show the method is effective and efficient. Comparisons of TOA snow reflectance before and after anisotropic correction show that the systematic and large variation of snow reflectance across the scan lines of an image due to satellite viewing/illumination geometry can either be eliminated or greatly reduced by applying the correction algorithm.